console.log(String(1) === new String(1))
let colors = ["red", "green", "blue"];
let removed = colors.splice(1, 2, "yellow", "orange")
console.log(colors) // red,yellow,orange,green,blue
console.log(removed) // []
let numbers = [1, 2, 3, 4, 5, 4, 3, 2, 1];
// foreach
let a = numbers.forEach((item, index, array) => {
    // 执行某些操作
    return array[index] = item*10
});
console.log(a,numbers)
  